Analysis of vasomotion waveform changes during pressure reduction and adenosine application.
Changes in the vasomotion waveform were studied in transverse arterioles (TAs) and their first-order side branches (FOSs) in the tenuissimus muscle of 14 young, anesthetized rabbits during stepwise arterial pressure reduction and local application of adenosine using intravital video microscopy. Pressure reduction resulted in a systematic increase in vasomotion cycle length (CL) and amplitude (A) concomitant with an increase in effective vascular diameter (Deff) and maximum diameter and a decrease in blood flow (Q). During adenosine application Deff and maximum diameter also increased, but CL and A did not change systematically. At moderate pressure reductions and during adenosine application CL changes were limited (less than 1.5 s) and nonsystematic, agreeing with an earlier study (D. W. Slaaf, G. J. Tangelder, H. C. Teirlinck, and R. S. Reneman. Microvasc. Res. 33: 71-80, 1987). In TAs these changes resulted from changes in both the dilation and the constriction phase. In FOSs, however, changes in CL were caused by prolongation of the dilation phase alone. At greatly reduced pressure levels, the CL increase was more pronounced and in both TAs and FOSs was caused by plateau formation in the dilation phase. Stretch of the arteriolar wall does not seem to play a role in control of the vasomotion waveform. Because the onsets of dilation always occur synchronously in TAs and FOSs, but the onsets of constriction do not, vasomotion seems to be a series of rhythmic dilations.
Oude Vrielink
H H
HH
Department of Physiology, University of Limburg, Maastricht, The Netherlands.
Slaaf
D W
DW
Tangelder
G J
GJ
Weijmer-Van Velzen
S
S
Reneman
R S
RS
D000241:Adenosine / Q000494:pharmacology*; D000818:Animals; D001160:Arterioles / Q000502:physiology; D001794:Blood Pressure / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D005260:Female; D008297:Male; D008955:Models, Cardiovascular; D009994:Osmolar Concentration; D011817:Rabbits; D014661:Vasoconstriction; D014664:Vasodilation; D014666:Vasomotor System / Q000502:physiology*
D000241:Adenosine